The present invention relates generally to the field of device tracking for medical imaging. In particular, the invention relates to methods and systems for correcting motion artifacts in imaging applications using device tracking.
Several imaging techniques for example, X-ray fluoroscopy, Computed Tomography (CT), Ultrasound, and Magnetic Resonance (MR) imaging employ the use of a device placed inside or on the patient during diagnostic, therapeutic or surgical medical procedures. These procedures typically take a long time resulting in inconvenience and the possibility of exposure to extra dosage in case of X-rays. MR imaging eliminates the dosage issue but it has been most successful in applications in which motion is minimal. Since the frame of reference in the MR scanner is the gradient coil system, small changes in the position of anatomy cause image blurring. This is particularly problematical for small Field-of-View (FOV) imaging where small motions can move MR signal sources over a substantial portion of the image.
MR imaging poses special challenges for acquisition of high-quality images from a vessel wall for example a blood vessel wall inside the patient. To maximize the Signal-to-Noise Ratio (SNR), intravascular imaging coils are frequently used. In vessels such as the coronary arteries, however, this SNR gain is overshadowed by the extreme motion caused by the cardiac cycle and respiration. There is a clear need for imaging strategies that can overcome this limitation.
MR tracking has been used for several years to control the imaging plane of the scanner. This technique has been called “Guided Scan” and has proven very successful for applications as diverse as dynamic joint imaging and vascular localization. With this method a device (e.g. a catheter) is located and the measured coordinates are immediately used to control the scan plane location of one or more subsequent images. Although the localization is relatively fast, patient or anatomic motion during image acquisition can result in severe image artifacts.
There is a continuing need, therefore, for improvements in device tracking techniques that address motion artifacts in image acquisition.